How did the ancient Greek find out the Earth was round?

Answer by  dollgirl (636)

The Greeks made the observation that during an eclipse, the Earth casts a spherical shadow on the moon. Eratosthenes assumed that the Earth is round and was able to calculate the circumference of the earth at about 40,320 kilometers, which was fairly close to today's mean value of 40,030 kilometers.

Answer by  Prof (10)

One method was to measure the length of a shadow cast by a measured object at noon, at two different latitudes (for instance, one in Greece and one in Egypt).

Answer by  Zuzu (200)

Greek philosophers believed that all heavenly bodies were spherical, but Aristotle stated that travellers voyaging south could see southern constellations rise higher above the horizon. He also noted that the shadow of the earth on the moon is a curved shape. These could only be if the earth was round.